Apply a Sequence of Updates

Immutable Statemedium

Course · Section 9: Data Structures, Modern Operators and Strings · Lecture 111: The Spread Operator (...)

Implement `applyUpdates(state, updates)` that folds an array of partial-state patches onto `state`, returning the new state without mutating the original.

Examples

Input: state { a:1, b:2 }, updates [{ b:3 }, { c:4 }]

Output: result { a:1, b:3, c:4 }, original unchanged

Each patch merges immutably; the original object is never modified.

Sample tests

Input: merges patches, leaves original

Output: [{"a":1,"b":3,"c":4},{"a":1,"b":2}]

Input: later patches win

Output: {"x":3}

+ 1 hidden test run on Submit.

Hints

Common pitfalls

Mutating state with Object.assign(state, patch) changes the caller's object.

Learning resources

React: Updating Objects in State

Approach & explanation (try first)

Folding patches with spread produces a new merged object each step, the immutable batched-update pattern.

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Run your code to see results.

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